Built a treehouse with my 7yr old and it actually didn't fall down

So this has been on my son's wish list forever and I finally committed to it last weekend. Spent Saturday morning gathering supplies from my neighbor's old deck he was tearing down. Sunday we went to town, got some 2x6s and bolts. Nothing fancy, just a platform maybe 8 feet up in the big oak out back. My kid did about 40% of the work which meant it took twice as long but man, seeing his face when we nailed in the last board was worth every minute. Still has railings to install but he's already spending all his time up there with his binoculars.